Inspection devices of the prior art, whether for use in inspecting containers such as glass bottles or whether for inspecting other types of articles, have been of four basic types.
In a first type of inspection device for use in inspecting articles being moved by a conveyor line, electrical switches of the mechanically actuated type have been used to signal the presence of out-of-tolerance articles. An early device of this type is taught by Wagner in U.S. Pat. No. 1,758,268 in which mechanically actuated reed switches are used for the measuring and sorting of cores such as those which are used in the construction of relays and magnets. The use of mechanically actuated electrical switches in inspection devices is also taught by Fry et al. in U.S. Pat. No. 3,076,268 and by Wolford, U.S. Pat. No. 3,080,659, both of which pertain to inspection devices for bottles or containers.
In a second type of prior art device, Roberson, in U.S. Pat. No. 3,537,579, shows and describes a container gauging and sorting apparatus in which the progression of containers or bottles along a conveyor line is stopped by oversized containers which will not pass between a pair of fixed plates. Stoppage of Roberson's conveyor line is effective to signal the reject mechanism and to eject the out-of-tolerance container.
In a third type of prior art inspection device, Stein, in U.S. Pat. No. 3,814,241, teaches the use of a transducer, which includes an armature and coil, for providing a signal to indicate out-of-tolerance containers.
In the fourth type of prior art construction, as taught by DeTar in U.S. Pat. No. 2,504,505, and by Luhn et al., in U.S. Pat. No. 3,031,075, photoelectric sensors are used to provide an out-of-tolerance signal for articles being measured.
The present invention utilizes an optical gauging device that includes a photoelectric sensor and a transducer for varying the quantity of light that reaches the photoelectric cell in accordance with minimum and maximum size limitations for the container or bottle.
The transducer is simple and durable, eliminating the complexity of previous photoelectric sensor inspection devices and also eliminating failure problems that are associated with mechanically actuated electrical switches.